Suction cups are generally well-known and commonly used to mount and secure objects to smooth surfaces such as the surfaces of glass, plastic, Formica, glazed tile, metal, and other smooth surfaces. A typical suction cup includes a cup body and a stem. The cup body is generally arcuate or circular and defines a concavity. Typically, the stem is integrally formed on the body and used as the place of attachment for the object to be supported by the suction cup. At least the body of the suction cup is made of rubber, plastic or other material having sufficiently elastically resilient properties such that, when the body is pressed against a smooth surface, the volume of concavity is reduced, thereby forcing air to be expelled so that the body forms an air-tight seal against the smooth surface. Atmospheric pressure outside the body retains the suction cup body against the surface. When the air-tight seal is broken, air rushes into the concavity, releasing the vacuum and the suction attachment to the surface. Whereupon the elastically resilient material of the suction cup body returns to its relaxed condition. The resilient suction cup can be repeatedly reused.
Suction cups are difficult to properly position. Once a suction cup is attached to a surface, the suction forces (atmospheric and friction) resist repositioning of the cup. Attachment of the suction cup to an object can also be a problem. Preferably, the attachment should be releasable.
Furthermore, the vacuum within the suction cup resists the resilient force of the body so that the force of suction balances the resilient force of the body of the suction cup. The result is a limit on the degree of vacuum which can be achieved.
One way this limitation on the vacuum can be at least partially overcome is by “pulling” the center of the suction cup body away from the surface, thereby at least partially overcoming the restraining effect of the vacuum and generating an even greater vacuum. The periphery of the suction cup forms an air-tight seal with the surface. When the center of the suction cup body is pulled resiliently away from the surface, a partial vacuum is formed between the body and the surface so that the suction cup body “sticks” to the surface. The greater the vacuum the better the cup sticks to the surface.
Several devices have been proposed to “pull” the center of the suction cup away from the surface in order to increase the suction. The most common arrangement, often found for example on the bases of pencil sharpeners and many kitchen appliances, involves a rod or crankshaft which extends mainly parallel to the surface to which the suction cup is to adhere. The center of the suction cup is attached to an eccentric section of the rod or crankshaft, and when a lever arm is turned, the center of the suction cup is pulled outward. U.S. Pat. No. 2,089,714, HOLDING DEVICE, issued Aug. 10, 1937, to Schuler; U.S. Pat. No. 3,765,638, SUCTION MOUNT, issued Oct. 16, 1973, to Harrison; and U.S. Pat. No. 4,934,641, CURVED SURFACE SUCTION MOUNTING APPARATUS, issued Jun. 19, 1990, to McElhaney, all of which are incorporated herein by reference, all describe such shaft-based arrangements.
One problem with arrangements using crankshafts and eccentric rods is the lever arms which extend out from whatever device they are mounted in. The lever arms is all too easy to hit or snagged, and the suction is thereby accidentally released. Another drawback of lever arms is that the support and bearing structure for them is difficult to integrate into the structure of the device which is utilizing the suction cups. This complication increases costs and the likelihood of failure.
A further cause of increased costs associated with such suction cup assemblies according to the prior art is that they usually require suction cups that must be specially designed to accommodate the lever arms, crankshafts, and the like.
More recently, U.S. Pat. No. 5,087,005, TWIST-CAM SUCTION CUP ASSEMBLY, issued Feb. 11, 1992, to Holoff, et al. and U.S. Pat. No. 5,381,990, RELEASABLE SUCTION CUP ASSEMBLY, issued Jan. 17, 1995, to Belokin, et al., both incorporated herein by reference, proposed devices for “pulling” the center of the suction cup axially.
Holoff, et al., for example, discloses a suction cup assembly having a suction cup, a cam member, a cone member and a mating core member secured to the suction cup. The cone member has an outer periphery generally co-extensive with an outer portion of the suction cup, and a generally cylindrical inner opening closely enclosing a cylindrical outer surface of the core member. The cam member has generally cylindrical camming surfaces, and is mounted onto and closely engages either the core member or a camming flange on the cone member, depending on the embodiment. The cam member axially shifts the core member outward relative to the cone member by pulling the center of the suction cup away from a surface to which the suction cup may be adhered.
Belokin, et al. discloses a releasable suction cup formed by a cup body which has a duct passing therethrough and a valve element for opening the duct, whereby the vacuum holding the suction cup can be released for repositioning the suction cup. The valve extends through the duct and is threaded on one end to receive a threaded fastener which is used to move the valve element into a sealing position and to secure the suction cup to an object.
The axial suction cup devices of Holoff, et al. and Belokin, et al. and others however are overly complex to manufacture, assemble and operate, as well as suffering other limitations.
Therefore, the inventor of the present invention invented the apparatus and method for a suction cup device as disclosed herein in FIGS. 1-6, and in U.S. Pat. No. 6,666,420 issued on Dec. 23, 2003, which is incorporated herein by reference, having a compact axial suction cup installation and release mechanism. The suction cup device includes a suction cup within a concave housing, and an axial drive member structured to operate on an external surface of the housing. A drive shaft is coupled to a central portion of the suction cup and extends through an aperture in the housing, projecting above a drive surface axially aligned with the concave surface formed in the housing. The drive shaft extends through a central aperture in the axial drive member and interacts with an inclined drive surface to pull the central portion of the suction cup toward and push it away from the concave surface of the housing when the axial drive member is rotated in first and second opposite directions relative to the housing.